Vortex fog generators



June 2, 1959 s'. P. HAYNES ET Al. 2,889,284 l' VORTEX FOG GENERATORS Filed March 10, 1951 l 3 Sheets-Sheet l \1-' ln f\ ff r\. g v \D Q s \0 Q Oro/e @Am/f D Q N k1 N nventors Q G50/P65 ,0. HA Y/vfs gl, 7l/m54 f7-WM il Qi z i 3 W l v- Gttornegs June 2, 1959 G. P. HAYNl-:s ETAL 2,889,284

voRTEx Foc GENERATORS --Filed Maren 1o, 1951 -3 sheets-sheet 2 it... L.

vJune 2, 1959 G. P. HAYNES Er'AL VORTEX Foc GENERAToRs 3 Sheets-Sheet 5 Filed March l0,` 1951 nventors nited States Patent Oce 2,889,284 Patented June 2, 1959 VORTEX FOG GENERATORS George P. Haynes, Hempstead, and Samuel Letvin, Elmhurst, N.Y., assignors to Thermo Projects Incorporated, a corporation of New York Application March 10, 1951, Serial No. 214,891 14 Claims. (Cl. 252-359) This invention relates to fog generators for generating and discharging a fog or cloud of vapor. The generator of the present invention is particularly suitable for continuous production of a large volume of fog as a protective screen for military use. It may also Ibe utilized for other purposes, as for providing a body of fog for protecting orchards against frost or for dispersing insecticides, fungicides, etc.

In the production of fog screens for military purposes, certain considerations are vital. One is that the fog generator must be able to operate for long periods of time without interruption for cleaning or purging. It is also important that when the ygenerator is shut down, there should be no afterglow or discharge of sparks or flames which might be visible to the enemy. It is also important to provide a generator in which the fog formation is uniform, in which the fuel and fogging materials are used without waste, and in which the temperatures of the parts are kept under control to secure reliable results and to prevent rapid destruction of the apparatus.

The nature and objects of the invention will be better understood from the description of one preferred illustrative embodiment of the invention shown in the accompanying drawings which form a part of this specification.

ln the drawings, Figure l is a view partly in side elevation and partly in vertical section of a fog generator embodying the invention;

Fig. 2 is a diagrammatic View showing the generator in plan and illustrating the piping connections thereto;

Fig. 3 is a vertical section on an enlarged scale showing the vortex cup or mixing chamber;

Fig. 4 is a transverse section on line 4 4 of Fig. 3;

Fig. 5 is a transverse section through the generator on line 5 5 of Fig. l;

Fig. 6 is a plan view of a nozzle for discharging the fogging substance; and

Fig. 7 is a side elevation on a larger scale of the discharge nozzle. y

Referring to the drawings in detail, the fog generator in the illustrative form shown comprises an outer casing 10 of generally cylindrical form having portions of two diameters. The casing 10 comprises a rear cylindrical portion 12 closed at the back by an end wall 14. A central section 16 of the casing is of slightly larger diameter than the cylinder 12 and is connected thereto by a flange or ring 18. A third portion of the casing 20 is of the same diameter as the portion 16 and is connected thereto by bolts 22 passing through flanges on the respective casing parts. The front portion of the casing comprises a curved breast 24 in the front of which is a central opening 26. Inside of the outer casing is an inner casing 27, the rear portion of which is a combustion chamber having a cylindrical rear section 28, a neck 30 of decreasing diameter and a cylindrical collar 32 at the end of theV neck. Mounted on the collar 32 is a ring or flange 34 forming a rear wall of a cooling or expansion chamber 36 which is partly cylindrical and at its front end has a sloping band portion 38 of decreasing diameter, the front edge of which fits against the inner wall of the breast portion 24 of the casing around the opening 26. An adjustable damper ring 40 is mounted in the combustion chamber near the front of the cylindrical part thereof, by which the size of the opening in this part of the combustion chamber may be increased or decreased. Mounted near the rear end of the combustion chamber is a wall 42 having a circular opening 44 therein. Mounted on the end wall 14 of the outer casing is a tube 46 of an oil burner, which is shown as having an inclined flange 48 at the front end thereof, which is contained within the opening in the plate 42, there being space for the entry of air around this flange, and through openings therein if such are provided. Mounted in the tube is an atomizer or spray nozzle 50 which may be of any suitable type, and also mounted on the tube and projecting through a hole in the flange 48 is an electric ignition device 52. Oil is forced under pressure to the spray nozzle through an oil pipe 54. The combustion chamber is provided with a series of inclined or tangentially disposed holes 56 through which air under pressure may enter from the space 58 between the casing wall 12 and the wall of the combustion chamber. This air supports the combustion of fuel sprayed into the chamber and also causes rapid rotation of the air and atomized oil to procure proper mixing and combustion thereof.

Mounted in the front end of the casing is the vortex cup or mixing chamber 60. This is shown as a cup of generally cylindrical form with a rear wall 62 and supported near its front end by a ring 64 secured over the opening 26 by bolts 66. The part of the cup extending into the gas chamber is of preferably cylindrical form and is provided with a multiplicity of tangentially inclined holes 68, through which hot gases will enter, and owing to the tangential arrangement will be caused to rotate rapidly in the cup, forming a central vortex. At the forward end of the cylindrical portion of the cup is an outwardly flaring portion 70 followed Iby an inclined portion 72 of contracting diameter which bounds a fog discharge orifice 74. The projecting portion of the cup is preferably enclosed by a ring of insulating material. vThe fogging substance, which may be oil or a vehicle carrying a chemical fog forming or treating agent, is introduced into the vortex cup through a suitable nozzle. In the construction shown, a nozzle pipe 76 is provided which projects laterally through the walls of the casings and the wall of the vortex chamber and has at its end a spray head or nozzle 78 which is located on the axis of the vortex chamber. As shown particularly in Figures 3, 4, 6 and 7, the nozzle pipe 76 terminates in a fitting 80, which is flattened on one side, as indicated at 82, and has a hole 84 therein. Mounted on the flattened portion 82 of the pipe is the spray nozzle head 78 which has a central bore 86 which communicates with a plurality of radial discharge orifices 88. The bore 86 is closed at its outer end so that all of the oil is discharged through the orifices 88. The side wall 90 of the nozzle head through which the orifices 88 open is preferably slightly sloped, as shown particularly in Fig. 6. The discharge nozzle is preferably so placed in the cup that it is near the rear wall thereof and faces the rear wall so that the oil is discharged in a radial and somewhat rearward direction, as appears clearly from Fig. 3. Oil or whatever other fogging substance is used is discharged into the nozzle pipe 76 through a feed pipe 92 (Fig. 2).

The form and arrangement of nozzle described injects the oil or other fogging substance uniformly on the side wall at the rear of the cup. The oil is then picked up by the rotating gas lm entering through the holes 68 and the oil and hot gases are mixed thoroughly by the vortex action of the cup, and the resultant mixture is projected from the cup as a fog. The rapid rotary action of the but prevents accumulations of deposit or carbonization of the fog oil on the inside of the cup. The described formation at the mouthof the cup comprising the divergent and` convergent walls 70 and 72 acts to homogenize the discharge from the cup, providing complete mixture of heated gas and fog, so that the fog discharge from the outlet is of a highly uniform character.

Mounted in the back of the cup is a gas inlet which may be termed a vacuum breaker. This bleeds a small amount of the heated gases into the center of the vortex in the cup. This prevents the formation of a vacuum or area of very low pressure in the center of the cup in which a small quantity of the fog vapor would remain. Such residual vapor might ignite when the unit is shut oi and cause a visible flash which would be very objectionable in the case of military operations. In the construction shown, the vacuum breaker comprises a short U-shaped pipe 94, the legs of which project through holes in the bottom 62 of the cup and are open to permit entrance of gases. At the center of the crosspiece of the U is a short projecting pipe 96 which opens into the center of the vortex cup.

A baffle plate 93 of circular outline is preferably mounted in the chamber 36 between the plate 34 and the back of the vortex cup. This baffle plate is supported on two-or more` radial arms 95 and serves to prevent direct impingement of the flames on the back of the vortex cup, so as to prevent overheating of the latter and possible ignition of the charge within the cup.

The necessary volume of air under pressure for operating the generator is supplied by blower 160, which forces the air through a pipe 102 connected to the casing near the front end thereof. The air then passes rearwardly in the space between the inner and outer casings, entering the combustion chamber through the ports 56 as already described. By introducing the cool air at the front end of the casing, such air circulates around the forward part of the inner casing constituting the cooling chamber, as it may be termed, and cools this part of the apparatus to some extent, thereby keeping the temperature of the vortex cup under control so as to prevent any danger of ignition of the oil vapor which is to be discharged as a fog, not as a flame. The cool air also acts as an insulator between the wall of the casing and acts to keep the outer casing from getting too hot. The air also prevents the combustion chamber itself from being heated to a destructive temperature. At the same time the air absorbs the surplus heat which is carried into the combustion chamber so as to secure a high thermal eficiency.

Any suitable manner of mounting the parts on a supporting structure and supplying the fuel and fogging oil may be employed. In the construction shown, the parts are mounted on a frame 106 which carries an electric motor 108 connectedto drive the blower 100 and also thel oil pump or pumps. In the construction shown separate sources of supply are used for the fuel for the burner and for the fogging substance, but obviously a single source could be used if the same oil were used for both purposes. Figure 2 shows diagrammatically a double supply system. The fogging oil is contained in a drum or reservoir 11G, from which it is drawn through a pipe 112 and strainer 113 by pump 114. The fogging oil passes through a fog oil shut-off valve 116V to the fogging oil feeding pipe 92. From the fog oil shut-off valve a return pipe 1l8.leads back to the oil drum. If the fog oil shut-ott valve is turned oif While the pump 114 is being driven, the oil is simply pumped back to the drum. Fuel for the burner is contained in the tank 120 from whichV it is drawn through the strainer 122 and pipe 124 to a fuel pump 125. From the pump the oil is pumped through a pipe 126, relief valve 128 and pipe 139 to the atomizer. An; excess of oil is usually pumped so that when the pressurerrises to a higher value than that for which the relief valve is set, the surplus oil will pass .4 through the return pipe 132 to the tank. Suitable gages are provided where needed.

The invention of the present application is a modification of or improvement upon the invention described in our application for U.S. Patent, Serial No. 689,158, tiled August 8, 1946, now Patent No. 2,599,465. The apparatus of the present invention is a very compact, efficient and simple construction embodying features adapting it particularly for the production offog screens for military purposes.

While one preferred embodiment ofthe invention has been illustrated and described in detail, it is to be understood that changes may be made therein and the invention embodied in other structures. It is not, therefore, the intention to limit the patent to the speciic construction illustrated, but to cover the invention broadly in whatever form its principles may be utilized.

We claim:

l. A fog generator comprising an elongated outer casing, an elongated inner casing in the outer casing and extending longitudinally but spaced from the side walls thereof, the inner casing having an open front end adjacent to the end of the outer casing, said end of the outer casing having an opening therein communicating with the interior of the inner casing, a mixing cup having its mouth extending through said opening, the body of the mixing cup extending into the inner casing, an oil atomizer mounted at the rear end of the casings and discharging atomized oil into the rear end of the inner casing, means for introducing air under pressure into the space between the inner and outer casings, air ports for admitting air from the space between the casings into the inner casing adjacent to the oil atomizer, gas ports in the ing cup for admitting hot gases from the forward part of the inner casing into the mixing cup, and means for introducing a fogging substance into the mixing cup.

2. A fog generator as claimed in claim l, in which the gas ports for admitting gases into the mixing cup are inclined to radii so as to produce a vortex in the cup.

3. A fog generator as claimed in claim l in which the air under pressure is introduced near the front end of the generator adjacent to the location of the mixing cup, air ports for admitting air from the space between the casing into the inner casing adjacent to the oil atomizer, gas ports in the mixing cup for admitting hot gases from the forward part of the inner casing into the mixing cup, and means for introducing a fogging substance into the mixing cup.

4. A fog generator as claimed in claim l in which the air ports for admitting air into the inner casing adjacent to the oil atomizer are inclined to radii so as to cause rotation of the air entering said part of the inner casing.

5. A fog generator as claimed in claim l in which there is a baftie disc of smaller diameter than the diameter of the inner casing mounted transversely in the inner casing back of the mixing cup.

6. A fog generator comprising an outer casing, an inner casing therein having walls spaced from the outer casing so as to provide an air space around the inner casing, a mixing cup mounted inside of and near one end of the inner casing, said cup having a discharge orice to the outer atmosphere, means for introducing a fogging substance into the mixing cup, means for introducing cool air under pressure into the space between said casings at a point adjacent to the location of the mixing cup, a combustion chamber, means for introducing fuel into said chamber, means for introducing air from the space between said casings into said combustion chamber, and means for conducting the hot combustion gases from said combustion chamber to the inner casing adjacent to the mixing cup, and ports for admitting said hot gasesinto the mixing cup.

7. A fog generator as claimed in claim 6 in which the ports for admitting gases into the mixing cup are inclined so as to produce a vortex in the mixing cup.

en r u 8. A fog generator comprising an outer casing, au inner casing therein having walls spaced from the outer casing so as to provide an air space around the inner casing, a mixing cup near one end of the inner casing having a discharge orifice to the outer atmosphere, means for introducing a fogging substance into the mixing cup, means for introducing air under pressure into the space between said casings adjacent to the location of the mixing cup, a combustion chamber, means for introducing fuel into said chamber, means for introducing air from the space between said casings into said combustion chamber, means for conducting the hot combustion gases from said combustion chamber to the inner casing adjacent to the mixing cup, ports for admitting said hot gases into the mixing cup, said ports being inclined so as to produce a vortex in the cup, and a vacuum breaker duct opening into the inner casing and having a discharge outlet located on the axis of said cup.

9. A fog generator as claimed in claim 8 in which the means for introducing the fogging substance into the mixing cup comprise a nozzle located axially of said cup between the back of the cup and the discharge orifice of the vacuum breaker duct.

10. A fog generator comprising an elongated outer casing, an elongated inner casing in the outer casing and extending longitudinally and spaced from the side Walls thereof, the rear part of the inner casing constituting a combustion chamber and the forward part of the inner casing constituting a cooling chamber, said casing parts being connected by a tapered neck portion, the end of which communicating with the cooling chamber is of smaller diameter than the end connecting with the combustion chamber, the inner casing having an open front end adjacent to the end of the outer casing, said end of the outer casing having an opening therein communicating with the interior of the inner casing, a mixing cup having its mouth extending through said opening, the body of the mixing cup extending into the inner casing, an oil atomizer mounted at the rear end of the casings and discharging atomized oil into the rear end of the inner casing, means for introducing air under pressure into the space between the inner and outer casings near the front end of the generator adjacent to the location of the mixing cup, air ports for admitting air from the space between the casings into the inner casing adjacent to the oil atomizer, gas ports in the mixing cup for admitting hot gases from the forward part of the inner casing into the mixing cup, and means for introducing a fogging substance into the mixing cup.

11. A fog generator as claimed in claim 10 in which the gas ports for admitting gases into the mixing cup are inclined to radii so as to produce a vortex in the cup and in which the means for introducing the fogging substance into the mixing cup comprise a nozzle located axially of said cup near the rear end thereof and having radially and rearwardly inclined discharge orifices.

12. In a fog generator, a casing, means for supplying hot gases under pressure to said casing, a mixing cup of generally cylindrical form mounted in the casing, said cup opening at one end into the atmosphere and having at the outer end thereof an outwardly ared section followed by an inwardly contracted section constituting the discharge orice of the cup, said cup having inclined orifices in the cylindrical wall thereof for admission of hot gases and having a spray nozzle located on the axis of the cup near the rear end thereof for admission pf a fogging substance, said nozzle having discharge orices therein directed in generally radial and rearwardly inclined directions.

13. The construction as claimed in claim 12 provided with a vacuum breaker duct having a discharge orifice located on the axis of the cup.

14. A fog generator comprising a casing, a means for supplying hot gases under pressure to said casing, a mixing cup mounted in the casing having a closed rear end, the front end of the mixing cup opening into the atmosphere, inclined ports in the cup wall through which the hot gases under pressure enter the cup and form a Vortex therein, means for introducing a fogging substance into the cup including a discharge nozzle located axially of the cup near the back thereof and having discharge orices directed radially outwardly and somewhat inclined towards the back of the cup, a U-shaped duct mounted on the back of the cup, the legs of the U projecting through said back and open to the interior ofthe casing, said duct having a discharge orifice located axially of the cup in front of the nozzle.

References Cited in the file of this patent UNITED STATES PATENTS 1,358,084 Leigh Nov. 9, 1920 2,070,038 Batt Feb. 9, 1937 2,352,677 Anderson July 4, 1944 2,476,171 Williams July 12, 1949 2,686,160 Kell et al. Aug. 10, 1954 

1. A FOG GENERATOR COMPRISING AN ELONGATED OUTER CASING, AN ELOGNATED INNER CASTING IN THE OUTER CASING AND EXTENDING LONGITUDINALLY BUT SPACED FROM THE SIDE WALLS THEREOF, THE INNER CASING HAVING AN OPEN FRONT END ADJACENT TO THE END OF THE OUTER CASING SAID END OF THE OUTER CASING HAVING AN OPENING THEREIN COMMUNICATING WITH THE INTERIOR OF THE INNER CASING, A MIXING CUP HAVING ITS MOUTH EXTENDING THROUGH SAID OPENING, THE BODY OF THE MIXING CUP EXTENDING INTO THE INNER CASING, AN OIL ATOMIZER MOUNTED AT THE REAR END OF THE CASINGS AND DISCHARGING ATOMIZED OIL INTO THE REAR END OF THE INNER CASING, MEANS FOR INTRODUCING AIR UNDER PRESSURE INTO THE SPACE BETWEEN THE INNER AND OUTER CASINGS, AIR PORTS FOR ADMITTING AIR FROM THE SPACE BETWEEN THE CASINGS INTO THE INNER CASINGS ADJACENT TO THE OIL ATOMIZER, GAS PORTS IN THE MIXING CUP FOR ADMITTING HOT GASES FROM THE FORWARD PART OF THE INNER CASING INTO THE MIXING CUP, AND MEANS FOR INTRODUCING A FOGGING SUBSTANCE INTO THE MIXING CUP. 